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What is relative energy deficiency in sport (REDs)?

Relative energy deficiency in sport (REDs) describes a syndrome of poor health and declining athletic performance that happens when athletes do not get enough fuel through food to support the energy demands of their daily lives and training. REDs can and does affect athletes of any gender and ability level.

Low energy availability is something many athletes experience after a particularly demanding practice or competition. With rest and hearty, nutritious meals, most athletes can replenish their energy stores and continue training in a healthy way. However, if an athlete continues to push themselves without refueling, the energy deficit grows more serious and, over time, takes a toll on their endurance, strength, health, and well-being.

If left untreated, REDs can impair systems throughout the body, including:

  • Reproductive health: disrupted menstruation (missed or abnormal periods) in women and low libido in men
  • Bone health: increased risk of stress fractures and early onset osteoporosis
  • Immunity: more infections and colds due to decreased immunity
  • Metabolism: the body converts food into energy more slowly
  • Cardiovascular (heart) health: low heart rate causing dizziness and the potential for long-term heart damage
  • Psychological health: moodiness, depression, and anxiety

Is REDs related to the female athlete triad?

The female athlete triad is a subset of REDs. It describes three interrelated conditions: disordered eating, irregular menstruation, and bone loss.

The International Olympic Committee advanced the concept of the female athlete triad with the term REDs in 2014. REDs covers the broader consequences of chronic low energy availability on an athlete’s health and performance. It also recognizes the fact that any athlete, regardless of gender, can experience this syndrome.

Like other demanding sports, speed skating can put athletes at risk of RED-S if they don't refuel properly between workouts.

Relative energy deficiency in sport: When athletes run on empty

A sports medicine psychologist describes how energy deficiency can creep up on athletes, and why REDs and explains why REDs and eating disorders are not the same thing.

Who is at risk of REDs?

Sports that tie athletic success to a thin body can increase an athlete’s risk of REDs. Sports such as figure skating, gymnastics, and diving, for instance, often emphasize ultra-slim body types that are unrealistic for many athletes. Sports with frequent weigh-ins, such as lightweight rowing and wrestling, increase the risk that athletes will severely cut back on calories to make weight. Endurance athletes, such as marathoners and cyclists, also experience REDs at high rates.

Regardless of the specific sport, a team’s culture can also contribute to REDs. A culture of body shaming — insulting an athlete’s weight or the shape of their body — or winning at all costs can push athletes to overexercise and under-fuel, ignoring hunger and other signals from their bodies to the detriment of their health.

REDs | Symptoms & Causes

What are the symptoms of REDs?

The symptoms of REDs include:

  • Fatigue
  • Rapid weight loss
  • Missed periods or delayed puberty (female athletes)
  • Low libido (male athletes)
  • Frequent illness
  • Hair loss
  • Trouble focusing
  • Trouble staying warm
  • Irritability and depression

REDs and athletic performance

Low energy availability may lead to short-term performance improvements, however, this effect is temporary. As REDs depletes their performance, many athletes train even harder, using up even more energy without giving their bodies the fuel or rest they need to get stronger.

REDs impairs athletic performance in the following ways:

  • Decreased muscle strength
  • Decreased endurance
  • Increased risk of injury
  • Decreased training response
  • Impaired judgement
  • Decreased coordination
  • Decreased concentration

REDs | Diagnosis & Treatments

How is REDs diagnosed?

Low energy availability can be difficult to diagnose and is often overlooked. Ideally, an athlete with symptoms of REDs should see a sports medicine specialist who takes an athlete’s overall health and well-being, not just an individual injury, into account when making care decisions.

The diagnosis typically begins with a medical history. The clinician may ask the athlete if they have any symptoms such as weakness, fatigue, frequent colds, or interrupted menstrual cycle. They’ll ask about the athlete’s sport and training history, including the number of hours they train per week, whether their training load has increased recently, and if the athlete has noticed a drop in performance. They’ll also ask about the athlete’s eating habits and attitudes toward food.

After the medical history, the doctor will perform a physical exam, which will include measuring blood pressure and heart rate.

Based on what they find, the clinician may rate the athlete as being high, moderate, or low risk for serious harm from REDs. This will help determine the athlete’s treatment plan.

  • An athlete may be considered high risk if they use extreme techniques to lose weight or have signs of a serious medical condition related to REDs.
  • An athlete may be considered at moderate risk if they have lost a significant amount of weight in the past month (5 to 10 percent of their body mass), have irregular periods, or a history of stress fractures.
  • An athlete is considered low risk if they have a healthy physique, don’t resort to unhealthy diet or exercise strategies, and are in overall good health.

How is REDs treated?

The goal of treatment for REDs is to enable an athlete to participate in sports at a safe and appropriate level, replenishing their energy reserves continuously to support their health and performance.

The athlete’s care team may include:

  • A physician, who will monitor and treat the athlete’s physical health
  • A dietitian, who will work with the athlete to understand how food provides fuel they need to reach their goals and how to establish healthy eating habits
  • A psychotherapist or psychologist, who will help the athlete address underlying issues and anxieties that may contribute to unhealthy exercise and eating habits

Depending on the athlete’s level of risk, they may need to stop training for a while or cut back on training until their health and energy levels are more stable. They may also have an eating plan designed to rebuild strength and vitality.

Is it possible to prevent REDs?

REDs is preventable, but true prevention requires a shift in sports culture. Coaches, team doctors, and other sports officials need to prioritize athlete’s health and well-being above all. To this end, Dr. Kathryn Ackerman, director of the Wu Tsai Female Athlete Program, and other specialists have called for the following:

  1. Increased awareness of the negative effects of low energy availability
  2. Safe standards for monitoring athletes’ body composition and weight
  3. Elimination of toxic training environments in which athletes are shamed for the size and shape of their bodies

How we care for REDs at Boston Children’s Hospital

The Wu Tsai Female Athlete Program takes a comprehensive approach to diagnosing, treating, and managing sports injuries in female athletes and sees athletes of any gender with low energy availability. We start by assessing the whole athlete, including exercise habits, hormonal balance, and nutritional needs — not just symptoms and injuries — to ensure peak performance. We educate young athletes on proper nutrition and its importance in athletic performance. We also educate other clinicians, coaches, and parents on the signs of REDs and how to intervene appropriately.

As the largest and most experienced pediatric and young adult sports medicine practice in the country, the Sports Medicine Division leads the way for innovation in the prevention and care of sports injuries. We work with athletes of all ages and abilities to help them train and compete at their best.

REDs | Programs & Services